1. Field of the Invention
The present invention relates to trolling motor depth finders and, more particularly, to an automatic switch for activating a depth finder.
2. Discussion of Background
A typical fishing boat is propelled through the water by an outboard engine located in the stern of the boat. Many fishing boats also have a trolling motor mounted at the bow on a folding frame for maintaining position of a boat against a current, near a river bank or in making small adjustments in the position of the boat while its occupants are fishing. The trolling motor is typically activated by pressing a foot pedal so that the fisherman does not have to put his rod down to activate the trolling motor. When not in use, the trolling motor is folded and stowed in a generally horizontal position on the bow deck. In use, the trolling motor is unfolded and placed in the water.
Usually the boat will have a depth finder as part of its instrumentation package, along with speedometer, gasoline gauge, oil pressure gauge, and so forth. This depth finder is designed to determine the depth of the body of water as the boat is propelled by the engine. Frequently, the trolling motor will also have a depth finder transducer carried in the motor head for detecting the presence of surfaces in the water, including the presence of fish.
In fishing, the boat is propelled by the engine to a likely fishing location with the engine. The engine is turned off and the trolling motor moved from its stowed position to its trolling position. The trolling motor is in its stowed position when its frame is folded with the motor head and depth finder transducer out of the water. The trolling motor is in its trolling position when unfolded with the motor head and depth finder transducer in the water. Fishing lines are then cast and the position of the boat maintained using the trolling motor. The depth finder transducer of the trolling motor is switched on at its control panel and the sensitivity selected for the depth of water at that location. When the fisherman decides to move to a different location or to return to the dock, he switches off the depth finder, moves the trolling motor from the trolling position to the stowed position, secures it, starts the engine and departs.
If the fisherman forgets to turn the trolling motor depth finder off, he will have to go to the front of the boat and turn it off. Moving about in a boat is a little precarious because of the inherent instability of a small boat on water where every movement increases the likelihood of an accident. If he completely forgets that he has left the depth finder on, there may be interference between the depth finder of the trolling motor and the depth finder of the boat itself. Both operate by transmitting an ultrasonic signal and listening for the echo of that signal from a surface. A transmitted signal from one depth finder can be interpreted as the echo from the other, leading to erroneous depth information.
Finally, as part of the depth finder of the trolling motor, the sensitivity switch associated with the on/off control of the depth finder. The sensitivity control is set for the depth of water where the fishing is taking place. A fisherman usually has favorit places to fish where the water depth is known to him. Each time he moves to that spot, the fisherman resets the snsitivity of the depth finder for that location.